1. Field of the Invention
The invention relates to device for controlling a coupling mechanism, and in particular to a motorised device which enables the conventional friction clutch of a motor vehicle which does not incorporate a conventional clutch pedal, to be controlled. A control device in accordance with the invention may also be suitable for operating a variable speed drive, a brake or similar mechanism.
2. Description of the Related Art
A motorised clutch control device of the above-mentioned kind is described, for example, in French Patent Application No. 84.08323 filed on 28th May 1984. A device of this kind mainly comprises an electric motor associated with a reduction gear, a member for activating the coupling mechanism (comprising, for example, a lever in the form of a fork, which is known per se) and a connection mechanism disposed in a housing between the motor and the activating member and comprising, inter alia, a toothed sector connected to the activating member, at least one pinion disposed between the motor shaft and the toothed sector, and a force moderator arrangement comprising a spring connected to a pinion which is in engagement with the toothed sector. The arrangement is such that the spring can assist the electric motor, which is of relatively small power, by moderating the force which the latter must provide along an engaging or disengaging stroke.
In these previous constructions the force moderator spring is a helical spring operating under tension and disposed in the housing.
A problem arises when fitting out a powerful vehicle in which substantial power has to be applied to the clutch, as in this case the force applied to the compensating spring increases to the point at which it eventually results in fatigue in the spring attachment end, which can cause it to break. A stronger spring has to be used, although the space required for mounting a stronger spring of this kind is often limited.
The object of the invention is to minimise this drawback.